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   1 /*
   2  *      IPv6 fragment reassembly
   3  *      Linux INET6 implementation
   4  *
   5  *      Authors:
   6  *      Pedro Roque             <roque@di.fc.ul.pt>
   7  *
   8  *      $Id: reassembly.c,v 1.26 2001/03/07 22:00:57 davem Exp $
   9  *
  10  *      Based on: net/ipv4/ip_fragment.c
  11  *
  12  *      This program is free software; you can redistribute it and/or
  13  *      modify it under the terms of the GNU General Public License
  14  *      as published by the Free Software Foundation; either version
  15  *      2 of the License, or (at your option) any later version.
  16  */
  17
  18 /*
  19  *      Fixes:
  20  *      Andi Kleen      Make it work with multiple hosts.
  21  *                      More RFC compliance.
  22  *
  23  *      Horst von Brand Add missing #include <linux/string.h>
  24  *      Alexey Kuznetsov        SMP races, threading, cleanup.
  25  *      Patrick McHardy         LRU queue of frag heads for evictor.
  26  *      Mitsuru KANDA @USAGI    Register inet6_protocol{}.
  27  *      David Stevens and
  28  *      YOSHIFUJI,H. @USAGI     Always remove fragment header to
  29  *                              calculate ICV correctly.
  30  */
  31 #include <linux/errno.h>
  32 #include <linux/types.h>
  33 #include <linux/string.h>
  34 #include <linux/socket.h>
  35 #include <linux/sockios.h>
  36 #include <linux/jiffies.h>
  37 #include <linux/net.h>
  38 #include <linux/list.h>
  39 #include <linux/netdevice.h>
  40 #include <linux/in6.h>
  41 #include <linux/ipv6.h>
  42 #include <linux/icmpv6.h>
  43 #include <linux/random.h>
  44 #include <linux/jhash.h>
  45
  46 #include <net/sock.h>
  47 #include <net/snmp.h>
  48
  49 #include <net/ipv6.h>
  50 #include <net/protocol.h>
  51 #include <net/transp_v6.h>
  52 #include <net/rawv6.h>
  53 #include <net/ndisc.h>
  54 #include <net/addrconf.h>
  55
  56 int sysctl_ip6frag_high_thresh = 256*1024;
  57 int sysctl_ip6frag_low_thresh = 192*1024;
  58
  59 int sysctl_ip6frag_time = IPV6_FRAG_TIMEOUT;
  60
  61 struct ip6frag_skb_cb
  62 {
  63         struct inet6_skb_parm   h;
  64         int                     offset;
  65 };
  66
  67 #define FRAG6_CB(skb)   ((struct ip6frag_skb_cb*)((skb)->cb))
  68
  69
  70 /*
  71  *      Equivalent of ipv4 struct ipq
  72  */
  73
  74 struct frag_queue
  75 {
  76         struct hlist_node       list;
  77         struct list_head lru_list;              /* lru list member      */
  78
  79         __u32                   id;             /* fragment id          */
  80         struct in6_addr         saddr;
  81         struct in6_addr         daddr;
  82
  83         spinlock_t              lock;
  84         atomic_t                refcnt;
  85         struct timer_list       timer;          /* expire timer         */
  86         struct sk_buff          *fragments;
  87         int                     len;
  88         int                     meat;
  89         int                     iif;
  90         struct timeval          stamp;
  91         unsigned int            csum;
  92         __u8                    last_in;        /* has first/last segment arrived? */
  93 #define COMPLETE                4
  94 #define FIRST_IN                2
  95 #define LAST_IN                 1
  96         __u16                   nhoffset;
  97 };
  98
  99 /* Hash table. */
 100
 101 #define IP6Q_HASHSZ     64
 102
 103 static struct hlist_head ip6_frag_hash[IP6Q_HASHSZ];
 104 static DEFINE_RWLOCK(ip6_frag_lock);
 105 static u32 ip6_frag_hash_rnd;
 106 static LIST_HEAD(ip6_frag_lru_list);
 107 int ip6_frag_nqueues = 0;
 108
 109 static __inline__ void __fq_unlink(struct frag_queue *fq)
 110 {
 111         hlist_del(&fq->list);
 112         list_del(&fq->lru_list);
 113         ip6_frag_nqueues--;
 114 }
 115
 116 static __inline__ void fq_unlink(struct frag_queue *fq)
 117 {
 118         write_lock(&ip6_frag_lock);
 119         __fq_unlink(fq);
 120         write_unlock(&ip6_frag_lock);
 121 }
 122
 123 /*
 124  * callers should be careful not to use the hash value outside the ipfrag_lock
 125  * as doing so could race with ipfrag_hash_rnd being recalculated.
 126  */
 127 static unsigned int ip6qhashfn(u32 id, struct in6_addr *saddr,
 128                                struct in6_addr *daddr)
 129 {
 130         u32 a, b, c;
 131
 132         a = saddr->s6_addr32[0];
 133         b = saddr->s6_addr32[1];
 134         c = saddr->s6_addr32[2];
 135
 136         a += JHASH_GOLDEN_RATIO;
 137         b += JHASH_GOLDEN_RATIO;
 138         c += ip6_frag_hash_rnd;
 139         __jhash_mix(a, b, c);
 140
 141         a += saddr->s6_addr32[3];
 142         b += daddr->s6_addr32[0];
 143         c += daddr->s6_addr32[1];
 144         __jhash_mix(a, b, c);
 145
 146         a += daddr->s6_addr32[2];
 147         b += daddr->s6_addr32[3];
 148         c += id;
 149         __jhash_mix(a, b, c);
 150
 151         return c & (IP6Q_HASHSZ - 1);
 152 }
 153
 154 static struct timer_list ip6_frag_secret_timer;
 155 int sysctl_ip6frag_secret_interval = 10 * 60 * HZ;
 156
 157 static void ip6_frag_secret_rebuild(unsigned long dummy)
 158 {
 159         unsigned long now = jiffies;
 160         int i;
 161
 162         write_lock(&ip6_frag_lock);
 163         get_random_bytes(&ip6_frag_hash_rnd, sizeof(u32));
 164         for (i = 0; i < IP6Q_HASHSZ; i++) {
 165                 struct frag_queue *q;
 166                 struct hlist_node *p, *n;
 167
 168                 hlist_for_each_entry_safe(q, p, n, &ip6_frag_hash[i], list) {
 169                         unsigned int hval = ip6qhashfn(q->id,
 170                                                        &q->saddr,
 171                                                        &q->daddr);
 172
 173                         if (hval != i) {
 174                                 hlist_del(&q->list);
 175
 176                                 /* Relink to new hash chain. */
 177                                 hlist_add_head(&q->list,
 178                                                &ip6_frag_hash[hval]);
 179
 180                         }
 181                 }
 182         }
 183         write_unlock(&ip6_frag_lock);
 184
 185         mod_timer(&ip6_frag_secret_timer, now + sysctl_ip6frag_secret_interval);
 186 }
 187
 188 atomic_t ip6_frag_mem = ATOMIC_INIT(0);
 189
 190 /* Memory Tracking Functions. */
 191 static inline void frag_kfree_skb(struct sk_buff *skb, int *work)
 192 {
 193         if (work)
 194                 *work -= skb->truesize;
 195         atomic_sub(skb->truesize, &ip6_frag_mem);
 196         kfree_skb(skb);
 197 }
 198
 199 static inline void frag_free_queue(struct frag_queue *fq, int *work)
 200 {
 201         if (work)
 202                 *work -= sizeof(struct frag_queue);
 203         atomic_sub(sizeof(struct frag_queue), &ip6_frag_mem);
 204         kfree(fq);
 205 }
 206
 207 static inline struct frag_queue *frag_alloc_queue(void)
 208 {
 209         struct frag_queue *fq = kzalloc(sizeof(struct frag_queue), GFP_ATOMIC);
 210
 211         if(!fq)
 212                 return NULL;
 213         atomic_add(sizeof(struct frag_queue), &ip6_frag_mem);
 214         return fq;
 215 }
 216
 217 /* Destruction primitives. */
 218
 219 /* Complete destruction of fq. */
 220 static void ip6_frag_destroy(struct frag_queue *fq, int *work)
 221 {
 222         struct sk_buff *fp;
 223
 224         BUG_TRAP(fq->last_in&COMPLETE);
 225         BUG_TRAP(del_timer(&fq->timer) == 0);
 226
 227         /* Release all fragment data. */
 228         fp = fq->fragments;
 229         while (fp) {
 230                 struct sk_buff *xp = fp->next;
 231
 232                 frag_kfree_skb(fp, work);
 233                 fp = xp;
 234         }
 235
 236         frag_free_queue(fq, work);
 237 }
 238
 239 static __inline__ void fq_put(struct frag_queue *fq, int *work)
 240 {
 241         if (atomic_dec_and_test(&fq->refcnt))
 242                 ip6_frag_destroy(fq, work);
 243 }
 244
 245 /* Kill fq entry. It is not destroyed immediately,
 246  * because caller (and someone more) holds reference count.
 247  */
 248 static __inline__ void fq_kill(struct frag_queue *fq)
 249 {
 250         if (del_timer(&fq->timer))
 251                 atomic_dec(&fq->refcnt);
 252
 253         if (!(fq->last_in & COMPLETE)) {
 254                 fq_unlink(fq);
 255                 atomic_dec(&fq->refcnt);
 256                 fq->last_in |= COMPLETE;
 257         }
 258 }
 259
 260 static void ip6_evictor(void)
 261 {
 262         struct frag_queue *fq;
 263         struct list_head *tmp;
 264         int work;
 265
 266         work = atomic_read(&ip6_frag_mem) - sysctl_ip6frag_low_thresh;
 267         if (work <= 0)
 268                 return;
 269
 270         while(work > 0) {
 271                 read_lock(&ip6_frag_lock);
 272                 if (list_empty(&ip6_frag_lru_list)) {
 273                         read_unlock(&ip6_frag_lock);
 274                         return;
 275                 }
 276                 tmp = ip6_frag_lru_list.next;
 277                 fq = list_entry(tmp, struct frag_queue, lru_list);
 278                 atomic_inc(&fq->refcnt);
 279                 read_unlock(&ip6_frag_lock);
 280
 281                 spin_lock(&fq->lock);
 282                 if (!(fq->last_in&COMPLETE))
 283                         fq_kill(fq);
 284                 spin_unlock(&fq->lock);
 285
 286                 fq_put(fq, &work);
 287                 IP6_INC_STATS_BH(IPSTATS_MIB_REASMFAILS);
 288         }
 289 }
 290
 291 static void ip6_frag_expire(unsigned long data)
 292 {
 293         struct frag_queue *fq = (struct frag_queue *) data;
 294         struct net_device *dev;
 295
 296         spin_lock(&fq->lock);
 297
 298         if (fq->last_in & COMPLETE)
 299                 goto out;
 300
 301         fq_kill(fq);
 302
 303         IP6_INC_STATS_BH(IPSTATS_MIB_REASMTIMEOUT);
 304         IP6_INC_STATS_BH(IPSTATS_MIB_REASMFAILS);
 305
 306         /* Don't send error if the first segment did not arrive. */
 307         if (!(fq->last_in&FIRST_IN) || !fq->fragments)
 308                 goto out;
 309
 310         dev = dev_get_by_index(fq->iif);
 311         if (!dev)
 312                 goto out;
 313
 314         /*
 315            But use as source device on which LAST ARRIVED
 316            segment was received. And do not use fq->dev
 317            pointer directly, device might already disappeared.
 318          */
 319         fq->fragments->dev = dev;
 320         icmpv6_send(fq->fragments, ICMPV6_TIME_EXCEED, ICMPV6_EXC_FRAGTIME, 0, dev);
 321         dev_put(dev);
 322 out:
 323         spin_unlock(&fq->lock);
 324         fq_put(fq, NULL);
 325 }
 326
 327 /* Creation primitives. */
 328
 329
 330 static struct frag_queue *ip6_frag_intern(struct frag_queue *fq_in)
 331 {
 332         struct frag_queue *fq;
 333         unsigned int hash;
 334 #ifdef CONFIG_SMP
 335         struct hlist_node *n;
 336 #endif
 337
 338         write_lock(&ip6_frag_lock);
 339         hash = ip6qhashfn(fq_in->id, &fq_in->saddr, &fq_in->daddr);
 340 #ifdef CONFIG_SMP
 341         hlist_for_each_entry(fq, n, &ip6_frag_hash[hash], list) {
 342                 if (fq->id == fq_in->id &&
 343                     ipv6_addr_equal(&fq_in->saddr, &fq->saddr) &&
 344                     ipv6_addr_equal(&fq_in->daddr, &fq->daddr)) {
 345                         atomic_inc(&fq->refcnt);
 346                         write_unlock(&ip6_frag_lock);
 347                         fq_in->last_in |= COMPLETE;
 348                         fq_put(fq_in, NULL);
 349                         return fq;
 350                 }
 351         }
 352 #endif
 353         fq = fq_in;
 354
 355         if (!mod_timer(&fq->timer, jiffies + sysctl_ip6frag_time))
 356                 atomic_inc(&fq->refcnt);
 357
 358         atomic_inc(&fq->refcnt);
 359         hlist_add_head(&fq->list, &ip6_frag_hash[hash]);
 360         INIT_LIST_HEAD(&fq->lru_list);
 361         list_add_tail(&fq->lru_list, &ip6_frag_lru_list);
 362         ip6_frag_nqueues++;
 363         write_unlock(&ip6_frag_lock);
 364         return fq;
 365 }
 366
 367
 368 static struct frag_queue *
 369 ip6_frag_create(u32 id, struct in6_addr *src, struct in6_addr *dst)
 370 {
 371         struct frag_queue *fq;
 372
 373         if ((fq = frag_alloc_queue()) == NULL)
 374                 goto oom;
 375
 376         fq->id = id;
 377         ipv6_addr_copy(&fq->saddr, src);
 378         ipv6_addr_copy(&fq->daddr, dst);
 379
 380         init_timer(&fq->timer);
 381         fq->timer.function = ip6_frag_expire;
 382         fq->timer.data = (long) fq;
 383         spin_lock_init(&fq->lock);
 384         atomic_set(&fq->refcnt, 1);
 385
 386         return ip6_frag_intern(fq);
 387
 388 oom:
 389         IP6_INC_STATS_BH(IPSTATS_MIB_REASMFAILS);
 390         return NULL;
 391 }
 392
 393 static __inline__ struct frag_queue *
 394 fq_find(u32 id, struct in6_addr *src, struct in6_addr *dst)
 395 {
 396         struct frag_queue *fq;
 397         struct hlist_node *n;
 398         unsigned int hash;
 399
 400         read_lock(&ip6_frag_lock);
 401         hash = ip6qhashfn(id, src, dst);
 402         hlist_for_each_entry(fq, n, &ip6_frag_hash[hash], list) {
 403                 if (fq->id == id &&
 404                     ipv6_addr_equal(src, &fq->saddr) &&
 405                     ipv6_addr_equal(dst, &fq->daddr)) {
 406                         atomic_inc(&fq->refcnt);
 407                         read_unlock(&ip6_frag_lock);
 408                         return fq;
 409                 }
 410         }
 411         read_unlock(&ip6_frag_lock);
 412
 413         return ip6_frag_create(id, src, dst);
 414 }
 415
 416
 417 static void ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb,
 418                            struct frag_hdr *fhdr, int nhoff)
 419 {
 420         struct sk_buff *prev, *next;
 421         int offset, end;
 422
 423         if (fq->last_in & COMPLETE)
 424                 goto err;
 425
 426         offset = ntohs(fhdr->frag_off) & ~0x7;
 427         end = offset + (ntohs(skb->nh.ipv6h->payload_len) -
 428                         ((u8 *) (fhdr + 1) - (u8 *) (skb->nh.ipv6h + 1)));
 429
 430         if ((unsigned int)end > IPV6_MAXPLEN) {
 431                 IP6_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
 432                 icmpv6_param_prob(skb,ICMPV6_HDR_FIELD, (u8*)&fhdr->frag_off - skb->nh.raw);
 433                 return;
 434         }
 435
 436         if (skb->ip_summed == CHECKSUM_COMPLETE)
 437                 skb->csum = csum_sub(skb->csum,
 438                                      csum_partial(skb->nh.raw, (u8*)(fhdr+1)-skb->nh.raw, 0));
 439
 440         /* Is this the final fragment? */
 441         if (!(fhdr->frag_off & htons(IP6_MF))) {
 442                 /* If we already have some bits beyond end
 443                  * or have different end, the segment is corrupted.
 444                  */
 445                 if (end < fq->len ||
 446                     ((fq->last_in & LAST_IN) && end != fq->len))
 447                         goto err;
 448                 fq->last_in |= LAST_IN;
 449                 fq->len = end;
 450         } else {
 451                 /* Check if the fragment is rounded to 8 bytes.
 452                  * Required by the RFC.
 453                  */
 454                 if (end & 0x7) {
 455                         /* RFC2460 says always send parameter problem in
 456                          * this case. -DaveM
 457                          */
 458                         IP6_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
 459                         icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 460                                           offsetof(struct ipv6hdr, payload_len));
 461                         return;
 462                 }
 463                 if (end > fq->len) {
 464                         /* Some bits beyond end -> corruption. */
 465                         if (fq->last_in & LAST_IN)
 466                                 goto err;
 467                         fq->len = end;
 468                 }
 469         }
 470
 471         if (end == offset)
 472                 goto err;
 473
 474         /* Point into the IP datagram 'data' part. */
 475         if (!pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data))
 476                 goto err;
 477
 478         if (pskb_trim_rcsum(skb, end - offset))
 479                 goto err;
 480
 481         /* Find out which fragments are in front and at the back of us
 482          * in the chain of fragments so far.  We must know where to put
 483          * this fragment, right?
 484          */
 485         prev = NULL;
 486         for(next = fq->fragments; next != NULL; next = next->next) {
 487                 if (FRAG6_CB(next)->offset >= offset)
 488                         break;  /* bingo! */
 489                 prev = next;
 490         }
 491
 492         /* We found where to put this one.  Check for overlap with
 493          * preceding fragment, and, if needed, align things so that
 494          * any overlaps are eliminated.
 495          */
 496         if (prev) {
 497                 int i = (FRAG6_CB(prev)->offset + prev->len) - offset;
 498
 499                 if (i > 0) {
 500                         offset += i;
 501                         if (end <= offset)
 502                                 goto err;
 503                         if (!pskb_pull(skb, i))
 504                                 goto err;
 505                         if (skb->ip_summed != CHECKSUM_UNNECESSARY)
 506                                 skb->ip_summed = CHECKSUM_NONE;
 507                 }
 508         }
 509
 510         /* Look for overlap with succeeding segments.
 511          * If we can merge fragments, do it.
 512          */
 513         while (next && FRAG6_CB(next)->offset < end) {
 514                 int i = end - FRAG6_CB(next)->offset; /* overlap is 'i' bytes */
 515
 516                 if (i < next->len) {
 517                         /* Eat head of the next overlapped fragment
 518                          * and leave the loop. The next ones cannot overlap.
 519                          */
 520                         if (!pskb_pull(next, i))
 521                                 goto err;
 522                         FRAG6_CB(next)->offset += i;    /* next fragment */
 523                         fq->meat -= i;
 524                         if (next->ip_summed != CHECKSUM_UNNECESSARY)
 525                                 next->ip_summed = CHECKSUM_NONE;
 526                         break;
 527                 } else {
 528                         struct sk_buff *free_it = next;
 529
 530                         /* Old fragment is completely overridden with
 531                          * new one drop it.
 532                          */
 533                         next = next->next;
 534
 535                         if (prev)
 536                                 prev->next = next;
 537                         else
 538                                 fq->fragments = next;
 539
 540                         fq->meat -= free_it->len;
 541                         frag_kfree_skb(free_it, NULL);
 542                 }
 543         }
 544
 545         FRAG6_CB(skb)->offset = offset;
 546
 547         /* Insert this fragment in the chain of fragments. */
 548         skb->next = next;
 549         if (prev)
 550                 prev->next = skb;
 551         else
 552                 fq->fragments = skb;
 553
 554         if (skb->dev)
 555                 fq->iif = skb->dev->ifindex;
 556         skb->dev = NULL;
 557         skb_get_timestamp(skb, &fq->stamp);
 558         fq->meat += skb->len;
 559         atomic_add(skb->truesize, &ip6_frag_mem);
 560
 561         /* The first fragment.
 562          * nhoffset is obtained from the first fragment, of course.
 563          */
 564         if (offset == 0) {
 565                 fq->nhoffset = nhoff;
 566                 fq->last_in |= FIRST_IN;
 567         }
 568         write_lock(&ip6_frag_lock);
 569         list_move_tail(&fq->lru_list, &ip6_frag_lru_list);
 570         write_unlock(&ip6_frag_lock);
 571         return;
 572
 573 err:
 574         IP6_INC_STATS(IPSTATS_MIB_REASMFAILS);
 575         kfree_skb(skb);
 576 }
 577
 578 /*
 579  *      Check if this packet is complete.
 580  *      Returns NULL on failure by any reason, and pointer
 581  *      to current nexthdr field in reassembled frame.
 582  *
 583  *      It is called with locked fq, and caller must check that
 584  *      queue is eligible for reassembly i.e. it is not COMPLETE,
 585  *      the last and the first frames arrived and all the bits are here.
 586  */
 587 static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff **skb_in,
 588                           struct net_device *dev)
 589 {
 590         struct sk_buff *fp, *head = fq->fragments;
 591         int    payload_len;
 592         unsigned int nhoff;
 593
 594         fq_kill(fq);
 595
 596         BUG_TRAP(head != NULL);
 597         BUG_TRAP(FRAG6_CB(head)->offset == 0);
 598
 599         /* Unfragmented part is taken from the first segment. */
 600         payload_len = (head->data - head->nh.raw) - sizeof(struct ipv6hdr) + fq->len - sizeof(struct frag_hdr);
 601         if (payload_len > IPV6_MAXPLEN)
 602                 goto out_oversize;
 603
 604         /* Head of list must not be cloned. */
 605         if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC))
 606                 goto out_oom;
 607
 608         /* If the first fragment is fragmented itself, we split
 609          * it to two chunks: the first with data and paged part
 610          * and the second, holding only fragments. */
 611         if (skb_shinfo(head)->frag_list) {
 612                 struct sk_buff *clone;
 613                 int i, plen = 0;
 614
 615                 if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL)
 616                         goto out_oom;
 617                 clone->next = head->next;
 618                 head->next = clone;
 619                 skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
 620                 skb_shinfo(head)->frag_list = NULL;
 621                 for (i=0; i<skb_shinfo(head)->nr_frags; i++)
 622                         plen += skb_shinfo(head)->frags[i].size;
 623                 clone->len = clone->data_len = head->data_len - plen;
 624                 head->data_len -= clone->len;
 625                 head->len -= clone->len;
 626                 clone->csum = 0;
 627                 clone->ip_summed = head->ip_summed;
 628                 atomic_add(clone->truesize, &ip6_frag_mem);
 629         }
 630
 631         /* We have to remove fragment header from datagram and to relocate
 632          * header in order to calculate ICV correctly. */
 633         nhoff = fq->nhoffset;
 634         head->nh.raw[nhoff] = head->h.raw[0];
 635         memmove(head->head + sizeof(struct frag_hdr), head->head,
 636                 (head->data - head->head) - sizeof(struct frag_hdr));
 637         head->mac.raw += sizeof(struct frag_hdr);
 638         head->nh.raw += sizeof(struct frag_hdr);
 639
 640         skb_shinfo(head)->frag_list = head->next;
 641         head->h.raw = head->data;
 642         skb_push(head, head->data - head->nh.raw);
 643         atomic_sub(head->truesize, &ip6_frag_mem);
 644
 645         for (fp=head->next; fp; fp = fp->next) {
 646                 head->data_len += fp->len;
 647                 head->len += fp->len;
 648                 if (head->ip_summed != fp->ip_summed)
 649                         head->ip_summed = CHECKSUM_NONE;
 650                 else if (head->ip_summed == CHECKSUM_COMPLETE)
 651                         head->csum = csum_add(head->csum, fp->csum);
 652                 head->truesize += fp->truesize;
 653                 atomic_sub(fp->truesize, &ip6_frag_mem);
 654         }
 655
 656         head->next = NULL;
 657         head->dev = dev;
 658         skb_set_timestamp(head, &fq->stamp);
 659         head->nh.ipv6h->payload_len = htons(payload_len);
 660         IP6CB(head)->nhoff = nhoff;
 661
 662         *skb_in = head;
 663
 664         /* Yes, and fold redundant checksum back. 8) */
 665         if (head->ip_summed == CHECKSUM_COMPLETE)
 666                 head->csum = csum_partial(head->nh.raw, head->h.raw-head->nh.raw, head->csum);
 667
 668         IP6_INC_STATS_BH(IPSTATS_MIB_REASMOKS);
 669         fq->fragments = NULL;
 670         return 1;
 671
 672 out_oversize:
 673         if (net_ratelimit())
 674                 printk(KERN_DEBUG "ip6_frag_reasm: payload len = %d\n", payload_len);
 675         goto out_fail;
 676 out_oom:
 677         if (net_ratelimit())
 678                 printk(KERN_DEBUG "ip6_frag_reasm: no memory for reassembly\n");
 679 out_fail:
 680         IP6_INC_STATS_BH(IPSTATS_MIB_REASMFAILS);
 681         return -1;
 682 }
 683
 684 static int ipv6_frag_rcv(struct sk_buff **skbp)
 685 {
 686         struct sk_buff *skb = *skbp;
 687         struct net_device *dev = skb->dev;
 688         struct frag_hdr *fhdr;
 689         struct frag_queue *fq;
 690         struct ipv6hdr *hdr;
 691
 692         hdr = skb->nh.ipv6h;
 693
 694         IP6_INC_STATS_BH(IPSTATS_MIB_REASMREQDS);
 695
 696         /* Jumbo payload inhibits frag. header */
 697         if (hdr->payload_len==0) {
 698                 IP6_INC_STATS(IPSTATS_MIB_INHDRERRORS);
 699                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, skb->h.raw-skb->nh.raw);
 700                 return -1;
 701         }
 702         if (!pskb_may_pull(skb, (skb->h.raw-skb->data)+sizeof(struct frag_hdr))) {
 703                 IP6_INC_STATS(IPSTATS_MIB_INHDRERRORS);
 704                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, skb->h.raw-skb->nh.raw);
 705                 return -1;
 706         }
 707
 708         hdr = skb->nh.ipv6h;
 709         fhdr = (struct frag_hdr *)skb->h.raw;
 710
 711         if (!(fhdr->frag_off & htons(0xFFF9))) {
 712                 /* It is not a fragmented frame */
 713                 skb->h.raw += sizeof(struct frag_hdr);
 714                 IP6_INC_STATS_BH(IPSTATS_MIB_REASMOKS);
 715
 716                 IP6CB(skb)->nhoff = (u8*)fhdr - skb->nh.raw;
 717                 return 1;
 718         }
 719
 720         if (atomic_read(&ip6_frag_mem) > sysctl_ip6frag_high_thresh)
 721                 ip6_evictor();
 722
 723         if ((fq = fq_find(fhdr->identification, &hdr->saddr, &hdr->daddr)) != NULL) {
 724                 int ret = -1;
 725
 726                 spin_lock(&fq->lock);
 727
 728                 ip6_frag_queue(fq, skb, fhdr, IP6CB(skb)->nhoff);
 729
 730                 if (fq->last_in == (FIRST_IN|LAST_IN) &&
 731                     fq->meat == fq->len)
 732                         ret = ip6_frag_reasm(fq, skbp, dev);
 733
 734                 spin_unlock(&fq->lock);
 735                 fq_put(fq, NULL);
 736                 return ret;
 737         }
 738
 739         IP6_INC_STATS_BH(IPSTATS_MIB_REASMFAILS);
 740         kfree_skb(skb);
 741         return -1;
 742 }
 743
 744 static struct inet6_protocol frag_protocol =
 745 {
 746         .handler        =       ipv6_frag_rcv,
 747         .flags          =       INET6_PROTO_NOPOLICY,
 748 };
 749
 750 void __init ipv6_frag_init(void)
 751 {
 752         if (inet6_add_protocol(&frag_protocol, IPPROTO_FRAGMENT) < 0)
 753                 printk(KERN_ERR "ipv6_frag_init: Could not register protocol\n");
 754
 755         ip6_frag_hash_rnd = (u32) ((num_physpages ^ (num_physpages>>7)) ^
 756                                    (jiffies ^ (jiffies >> 6)));
 757
 758         init_timer(&ip6_frag_secret_timer);
 759         ip6_frag_secret_timer.function = ip6_frag_secret_rebuild;
 760         ip6_frag_secret_timer.expires = jiffies + sysctl_ip6frag_secret_interval;
 761         add_timer(&ip6_frag_secret_timer);
 762 }